Circuit breaker



March 24, 1953 M. H. HOBBS ET AL 2,632,829

CIRCUIT BREAKER Filed Jan. 17, 1951 v l 25'/ 37 al I 'n 35 e, l, F

\ 27 ,LL-Y l, o I

" 5| 4? Insulation l 4;'

WITNl-:ssl-:s: lNvENToR f: i Z MauriceH.Hobbs,Rober1C.Dcknson ond Reymond dldzkow kl.

Patented Mar. 24, 1953 CIRCUIT BREAKER Maurice H. Hobbs and Robert C. Dickinson, Pittsburgh, and Raymond J. Idzkowski, Turtle Creek, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application January 17, 1951, Serial No. 206,446

(Cl. ZOO-162) 1 Claims.

This invention relates to circuit breakers and more particularly to contact means and to a bumper for circuit breakers.

An object of this invention is to provide a circuit breaker having relatively movable contact means with means for preventing rebound of the movable contact upon closure of the contact means.

Another object of the invention is to provide a high-speed circuit breaker having relatively movable contact means embodying improved means for deceleratng the moving contact and preventing rebound of the moving contact upon closure of said contact means.

The novel features that are considered characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to structure and operation, together with additional objects and advantages thereof, will be best understood from the following detailed description of one embodiment thereof when read in conjunction with the accompanying drawing.

In said drawing:

Figure 1 is a side elevational View of a circuit breaker embodying the principles of the invention.

Fig. 2 is an enlarged top plan view of the contacts shown in the closed position.

Fig. 3 is an enlarged fragmentary side elevational view of the contacts in the closed position.

Referring to Fig. l of the drawing, the circuit breaker comprises generally a back plate l l upon which the breaker mechanism is mounted, stationary contact means I3, movable contact means I5, closing mechanism indicated generally at I1 and trip-means indicated generally at I9.

The stationary contact means I3 is rigidly mounted on the inner end of an insulating bushing 2l supported on and extending through the back plate Il. A rod 23 of conducting material extends through the bushing 2l and serves as a terminal to connect the stationary contact I3 in an electrical circuit. The movable contact means comprises a pair of spaced contact blades 25 pivotally mounted on a conducting member 21. The member 21 is rigidly mounted on the inner end of an insulating bushing 29 which is mounted on and extends through the back plate ll. A terminal rod 3l of conducting material is electrically connected to the member 2l and extends outwardly through the bushing 29.

The contact blades 25 are disposed one on each side of the member 21 and are pivoted on a pivot pin 33 extending therethrough. The contact blades are operatively connected by means of a link 35 to one arm of a bell crank 31 the other arm of which is connected by means of a link 39 to an operating lever 4|. The bell crank 31 is pivotally mounted on a bracket 43 secured to the back plate Il and the operating lever 4l is pivotally mounted on a bracket 45 also secured to the back plate Il.

A spring 41 tensioned between a fixed part of the breaker and a pin 49 on the operating lever 4I biases the latter in a clockwise direction. The operating lever 4I is releasably restrained against the bias of the spring 41 by means of a pivoted latch 5l forming a part of the trip device I9. The latch 5l is biased by means of a spring 53 into latching engagement with a latch roller carried on the free end of the operating lever 4I. The

latch 5l is pivoted on a pin 51 and is adapted to be actuated in a counterclockwise or unlatching direction by operation of a tripping electromagnet indicated generally at 59. The tripping electromagnet comprises an energizing winding 6l, a fixed core member 63 and a movable armature to which it attached a trip rod 61 extending upwardly through an opening in the core member 63 and adapted to engage a tail 69 of the latch 5l upon energization of the electromagnet.

The tripping electromagnet may be energized from any suitable source, for instance, in response to overload currents or by manually closing a suitable switch. When energized the electromagnet 59 attracts its armature 65 and thrusts the rod 61 upwardly to actuate the latch 5I to unlatching position whereupon the spring 41 moves the operating lever 4I sharply in a clockwise direction. This movement is transmitted through the link 39, bell crank 31 and thelink 35 to move the switch blade 25 to the open circuit position in which they are shown at 25 in Fig. 1.

The closing means I1 comprises a closing solenoid including an energizing winding 1I, a fixed core member 13 and a movable armature 15. The armature 15 is attached to a rod 11 which has its upper end pivotally mounted on the pin 49 thus connecting the armature 15 to the operating lever 4 i. When the latch 5| releases the operating lever 4l and this lever is moved to the open position to effect opening of the contacts 25|3, the armature 15 of the closing solenoid is moved upward to its unattracted position.

The circuit breaker is operated to the closed position by energization of the closing solenoid which may be effected in any suitable manner either manually or automatically. When energized the closing solenoid attracts its armature T and moves the operating lever II counter clockwise to its latched position (Fig. 1). During this movement the lever fil acts through the link 39, the bell crank 3l' and the link 35 to move the contact blades 25 to the closed position.

Referring to Fig. 2 of the drawing, it will be observed that in the closed position the contact blades 25 engage opposite sides of the stationary contact I3. The Contact blades 25 are provided with facing elongated contacts 'I9 disposed along their leading edges for engaging the stationary Contact I3 with a wiping action. In the open position the Contact blades 25 are. spaced apart by means of a spacer SI disposed therebetween and mounted on a bolt 83 which extends through openings in the switch blades. The bolt 83 is provided with a head 85 on one end and the. other end threadedly engages a nut tl'. Normal contact pressure is provided by means of aspring 89 compressed between Athe head 85 of the bolt 33 and` the. adjacent contact blade 2 5.

Rapid deceleration ofl thek contact blades by striking a rubber stop at the end ofY a high-speed closing operation causes contact bounce or rebound. The rebound forces are transmitted to the contact spring and sets up vibrations causing momentaryl loss ofspring pressure and consequent short separation of the contacts with the resultant arcing and` burning of the contacts. To overcome this difficulty there is provided an improved stop means which not only prevents contact bounce but increases the contact pressure at the end of the closing operation.

The stop means comprises a pair. of resilient stop members!!! (Figs. 2 and 3) disposed one on each side of the stationary contact I 3 and secured thereto by means of bolts 93 and nuts 9,5. The resilient stop'members 9| are preferably made of rubber or a rubber-like material. The

bolts 93. extend through openings in the stop members SI, the stationary contact I3 and plates 9.1 disposed one on the outside of each of the stop members SI. The inner edges of the stop membersSI are beveled Vas at 99 to, cooperate'with theU beveled edges IGI of the contact blades 25.

When the beveled edges BIH of the contact blades 25 engage the beveled edges .99, of the stop members SI during the latter part of the closing operation the resiliency of the stop members SI quickly decelerate vthe closing movement of the Contact blades "2,5 and the cooperating beveled edges of the stop member and the contact blades forces the Contact 19 against the stationary contact I3 thus increasing thecontaot pressure and preventing any tendency of the contact blades 25 t@ rebound or bounce The rubber. stop members and the contact blades are so Yarranged that the deceleration is a product of boththe elasticity'of the rubber and the friction between thecontact blades and the stop members. The deceleration occurs over an appreciable distance, hence, with a lesser rate and a lesser rebound force. The beveled edges of the contact blades and of the rubber stopV mem bers 'are inadesothat ythe mechanical advantage of the wedge `is used to transmitA a lateral :force to aid the contact spring force in maintaining conact pressure while the contact blades are being decelerated.

Having described the invention vin accordance with the patent statutes, YitY is to be understood that various changes and modifications may be made 'in nthe particular embodiment disclosed without departing from som'o'f the'essentialfeami@ @f QE? .iin/mention y H Y We claim. as our invention:

l. In a circuit breaker comprising rigid sta tionary contact means, movable contact means, a spring on said movable contact means normally providing contact pressure in the closed position of saidI contact means, operating mechanism for movingY said movable' contact means to closed position, a xed member of resilient material engageable by said movable contact for decelerating the closing movement of said movable contact and aaportion of said xed resilient member cooperating with said movable contact means to increase the contact pressure.

2. In a circuit breaker comprising rigid stationary. contact means, movable contact, means having a'beveled portion thereon, spring means on said movable contact means normally providigbontact pressure in the closed position of saidzcontact means, operating means for moving said movable Contact Ito the closed position, a xedmember or resilient material engageable by said movable contact means for decelerating the closing movement of said movable contact means, and said resilient member having a beveled' portion engageable bythe beveled portion of said movable contact means to increase the contact pressure near the end Aof theclosing operation.`

3. In a circuit breaker comprising rigidV` stationary contact means, movable contactinea'ns having a beveled.' 'portion Ythereon, 'a spring mounted onsaid movablecontact means normally providing contact pressure inthe closed posi'- tion of. said contactv means, a member oi resilient material'fixedly' mounted on saidsta'tionary contact means for decielerating the closing move ment 'of 'said"n iovableA contact means', said 'resilient member having a portion forming acute angle relative to isaidstationary contact means, andsaid beveled portion'of said movable Contact means coasting with said angular portion o said resilient member during the latter part of the closing loperation to prevent rebound of said movable contact means `and to increase the contact pressure.

fl. In a circuit breaker comprising a single rigid stationary contact member, movable contact means comprising a pair of spaced movable ccntect blades adapted '00, engage Opposite Sides. 0f said stationary Contact member, spring means on said movable contact blades normally providn ing contact pressure between both of said con tact blades and said stationary contact member in the closed position of said contacts, operating mechanism iol: moving said movable contact blade'stc open and closed positions, resilient stop means vcomprising. a'pair of members of resilient material lixedly mounted on said stationary contact member and disposed one on each side of said stationary contact member for dew celerating the 'closing movement'or said contact blades. each of said resilient members having a surface facing said stationary contact member and disposed at an anglethereto, and beveled sui/*faces'onV said chtact'blades cooperating with saidsurfaes' on rsaid resilient members duringr a closing' pera'ti ori to A prevent rebound of.. said contact blades 'and'to increase" said Contact presm sur@ 5. In a circuit breaker comprising a rigid elongatec'stausriaiy 'Contact member; movente "contact means' comprising a lpair 0f contact blades having beveled portions thereon; elongated contactson said' cont'act'blades disposed to rengage opposite sides of said stationary c'oi'itact'inemben spring. means on'said movable Contact blades providing contact pressure in the closed position of said contacts, operating mechanism for said movable contact means, resilient stop means comprising a member of resilient material xedly mounted on said stationary contact member disposed one on each side thereof for decelerating the closing movement of said Contact blades, each of said resilient members having a beveled surface for cooperating with the beveled edge of the corresponding contact blade during a closing operation to prevent rebound of said contact blades and to increase the contact pressure.

6. A circuit breaker comprising a rigid stationary contact member, movable contact means comprising a pair of spaced contact blades adapted to engage opposite sides of said rigid stationary contact member, a spring mounted on said movable contact blades for normally providing contact pressure between both of said movable contact blades and said rigid stationary contact member in the closed position of said contacts, operating mechanism for moving said movable contact blades to open and closed positions, stop means comprising blocks of resilient material mounted on said rigid stationary contact member on opposite sides thereof engageable by said contact blades for decelerating the closing movement of said contact blades, each of said blocks of resilient material having a surface facing the corresponding side of said rigid stationary contact and disposed at an acute angle relative thereto, and angular surfaces on said contact blades disposed to engage the angular surfaces on said resilient blocks in a manner to force said contact blades against the sides of said rigid stationary contact member to prevent rebound of said contact blades and to increase the contact pressure.

'7. In a circuit breaker comprising a rigid stationary contact member, a movable contact having a beveled portion thereon, a spring providing normal contact pressure in the closed position of said contact, stop means comprising a block of resilient material mounted on said rigid stationary contact member for decelerating the closing movement of said movable contact, said block of resilient material having a portion forming an acute angle relative to said rigid stationary contact member, and said beveled portion of said movable contact coasting with said angular portion of said resilient block during the latter portion of the closing operation to increase the normal contact pressure provided by said spring.

MAURICE H. HOBBS. ROBERT C. DICKINSON. RAYMOND J. IDZKOWSKI.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Number Name Date 1,901,493 Bowie Mar. 14, 1933 1,935,516 Musgrave Nov. 14, 1933 

